12v to 14.6 Volt DC-DC Charger with Lithium

[MarkMinNC]

I am trying to understand some things and hope you guys can offer some input.

I want to charge a standard 12v Lithium battery like a Chins or SOK in my truck. I want to keep the 12v amp draw to 10'ish amps or less. I am having a hard time finding a charger like this. Victron has one that will do 18 amps "charging" which I would assume would be close to 20 amps on the source 12v side but that is more charging load than I want.

I have found this which looks like it might (2/4/8 amp selector) work but I have some questions:

Automotive DC 12 Volt to 14.6 Volt Lithium Battery Charger

Charge your 12 volt lithium batteries with ease using our automotive DC 12V to 14.6V lithium battery charger. Shop now at Impulse Electronics for best charging solutions.

www.impulseelectronics.com

This charger does not have the "bulk/absorption" modes that a Victron or Renogy DC-to-DC charger would have. I do not quite understand the need for these modes with a Chins or SOK since the batteries built-in BMS is going to control all of this.

If I just left this Impulse 14.6v charger connected full time to the battery when I was driving or stopped, can I assume that the BMS in the battery will cut the charge load when the battery is full and then allow the charge to flow once the battery starts being discharged?

How does this work with a Victron/Renogy? I guess they know the battery is "full" when the BMS cuts the load and then they switch to a float mode of 13.6v?

I have looked for other 12v to 14.6 volt boost converters to basically do the same thing but there are not many of those out there either.

Any thoughts or ideas on how I can have a "charger" full time connected to a Chins/SOK and keep the amps in the 10'ish range would be greatly appreciated.

Mark

 

[sunshine_eggo]

I am trying to understand some things and hope you guys can offer some input.

I want to charge a standard 12v Lithium battery like a Chins or SOK in my truck. I want to keep the 12v amp draw to 10'ish amps or less. I am having a hard time finding a charger like this. Victron has one that will do 18 amps "charging" which I would assume would be close to 20 amps on the source 12v side but that is more charging load than I want.

I have found this which looks like it might (2/4/8 amp selector) work but I have some questions:

Automotive DC 12 Volt to 14.6 Volt Lithium Battery Charger

Charge your 12 volt lithium batteries with ease using our automotive DC 12V to 14.6V lithium battery charger. Shop now at Impulse Electronics for best charging solutions.

www.impulseelectronics.com

This charger does not have the "bulk/absorption" modes that a Victron or Renogy DC-to-DC charger would have. I do not quite understand the need for these modes with a Chins or SOK since the batteries built-in BMS is going to control all of this.

No it won't. the BMS doesn't "control" anything. it's just a guard dog. If something goes out of limits, it barks and shuts everything down. it will not "control" or regulate in any way.

If I just left this Impulse 14.6v charger connected full time to the battery when I was driving or stopped, can I assume that the BMS in the battery will cut the charge load when the battery is full and then allow the charge to flow once the battery starts being discharged?

No. Your battery BMS may not cut-off at 14.6V, and even if it does, in both cases, you don't want the battery held at 14.6V for extended periods. It's not good for them. You want the charger to recognize when the battery is full and stop charging.

Relying on the BMS as a part of normal operations is a big no-no. You want your equipment to operate INSIDE the BMS envelope. Regular and frequent triggering of BMS protection can wear them out.

How does this work with a Victron/Renogy? I guess they know the battery is "full" when the BMS cuts the load and then they switch to a float mode of 13.6v?

No, they conduct a bulk/absorption and float charge. You can set the Victron to lower voltages if you prefer. If the BMS cuts off, all they see is the battery suddenly being removed.

I have looked for other 12v to 14.6 volt boost converters to basically do the same thing but there are not many of those out there either.

Any thoughts or ideas on how I can have a "charger" full time connected to a Chins/SOK and keep the amps in the 10'ish range would be greatly appreciated.

If you absolutely don't want the right piece of equipment, but you want a super cheap option that makes some sense:

8-40V wide input converter to 13.8V. 13.8V is a very healthy voltage for long and slow LFP charging. You'll get it 98%+ full and never risk triggering the BMS if the battery cells are balanced.

 

[MT_Mike]

I am happy with the Victron 30 amp DC-DC charger I use in our camp trailer. I installed 2AWG 12 volt cables from the truck battery to the tailgate and have a separate connection to the Victron charger for charging two SOK 100AH batteries. You definitely need a smart charger configured correctly for charging Lipo4 batteries.

I also have a 96AH battery using 6 x 16AH Miady batteries in parallel. The 16AH Miady batteries ($50 each, two years ago) have a very cheap BMS and are specification rated for .2C charging approximately 3amp per battery. I found via trial and error the cheap BMS modules really don't like the .2C/3 amp charge for very long and will shut down before fulling charging. Charging at 1.0 to 1.5 amp appears to work the best. I now charge the six pack of parallel connected batteries using a RDX1 Pro charger configured for Lipo4 charging at a rate of 6 to 9 amps. The RDX1 Pro supports charging modes using 120VAC or 12VDC-DC. Surprisingly the home brew 96 AH battery has held up very well and is used for powering a 55 LBS thrust trolling motor (about 45 amps at full throttle), C-Pap and lighting operation when camping or home power outages, and powering up my Ham radio equipment during power outages or for portable operation. Battery testing with a 40AH draw gets me a little over 2 hours of battery use. I use Anderson Power Pole connectors in various sizes for low to high current charging and load usage on all my batteries.